Electromagnetic induction heattreating apparatus



Feb. 8, 1949.

H. E. som-:s

ELECTROMAGNETIG INDUCTION vHEAT-TREATING APPARATUS e sheets-sheet 1 Filed Jan.. 1.151945 Howard E. .Somes mvEN'roR W 712/# ATroRNEY 5 5 4 S my, 8 5 6 0 M 0 e 9 w 75 55 5 m I' 2 m m 5 E. f T e Y A www 2 R E m 6 www n 6 9 529 Iu l 9 w m n 5 77 M u 7H 4 w m m A 1 :l1 HU. G w d M 1 o M A m H L u M m O |1 m 7., m13 m/ 1 llIrvU m T 0 0% m w m v mi 5 M lHll l s W l! 19% f |ll|||l. E m x |L|I H`PIM L1 \J x xL HViiils /I 9 3- |l. x H... w 1...|l3 |l 5 AAH/ww. ,l\ l! N 1| 4 I I/ 4 m www Y 3 M 1 I w \.II\HW l m l \\T\ I'IIII 7 Ill |||||\l I A m 5 3 |||l|m\ w, u 7 di uw E 1 7. i-- w 4 1. 4 l l w 1 l v7. n. ,wg 5 5 8, n c L b. .w f Y/ l. e n F, F

5 2u t m n 9 4 U 5 T 6 O j we s W T m MR f/VY Sw. Em En dN R ME E O on ww. n sm wl A am 0 Hw m N C I T E. 2 N 2 G 1, m R .mw a m1 M. 1 1 l ,8, m J I h d l e e F n.. l F l 5 t sw, n h 4 S w 2 m .6. T e A h R S n 6 P G N T. m... A E R S m.. M n .O N *S o n E W H D Cu. .`\\U.. T E W A l O m c E 9 m 1 9 1. m 1 11 n 8 J .w .w n F F HowarE, 30772195'l INVENTOR /M4 Z ATTORNEY Patented Feb. 8, 1949 ELECTROMAGNETIC INDUCTION BEAT- TREATING APPARATUS Howard E. Somes, Detroit, Mich., assigner, by mesne assignments, to The Ohio Crankshaft Company, Cleveland, Ohio, a corporation of Ohio Application January 11, 1945, Serial No. 572,316

17 Claims.

This invention relates to heat treating apparatus, more particularly to apparatus for heat 'treating circumferentially toothed articles such as gears, splines and the like, both external and internal, by induced electromagnetic heating currents.

The present invention is most importantly directed to non-progressive uniform heat treatment of such articles as are not susceptible of rotation relative to the heating coil. Although it has been possible heretofore to heat gear teeth and the like with a simple coil while providing rotation between the coil and gear, it nevertheless has been proven that due to poor coupling between the coil and the gear, longer times are required and considerable quantities of heat have to be stored up in the work-piece undergoing heat treatment in order that the roots of the teeth and the portions therebetween will reach a desired hardening temperature.

It is one of the objects of the present invention to provide an improved induction heating apparatus by means of which the hardness, the distribution of hardness and the consequent control of stresses in the tooth surfaces of circumferentially toothed articles may be accurately controlled.

Another object is to provide an induction heating apparatus utilizing a helical inducing coil wherein the coil and the article to be heated are not susceptible to rotation, means for compensating for and minimizing variations in heat application due to ilux variations incident to the necessity of providing insulation between the coil turns.

Another object is to provide improved apparatus of such construction that toothed articles can be uniformly and precisely inductively heated and quenched, that is, one in which the heating will be duplicated from tooth to tooth and from gear to gear.

A further object is t provide induction heating apparatus of the foregoing character wherein means is provided to eliminate the variation of ilux due to end turn conguration of the coil thus enabling the application to the gear and tooth surfaces of a uniform iiux throughout the diameter of the gear and the direction of high tain features of construction and combinations of parts to be hereinafter described with reference to the accompanying-drawings, and then claimed.

The foregoing objects are attained for the most part through the provision of an inducing coil having teeth which are substantially complementary to the teeth of the article to be heat treated and are arranged to register with the article teeth in predetermined spaced relation with respect thereto whereby all teeth and all corresponding tooth surfaces, including the root surfaces, are simultaneously heated to the same depth and simultaneously reach hardening temperature. In order to compensate for ilux variations incident to the necessity of providing insulation between the coil turns, means is provided for rapidly reciprocating the coil relative to the article while maintaining the predetermined spacing between the teeth of the article and those of the coil. In the case of spiral teeth,

means is provided for effecting a controlled oscillatory movement of the coil during this reciprocation through the provision of cooperating splrally splined guide elements such that the coil teeth move in a direction parallel to the teeth of the article being heat treated. In addition, the coil is made of such length that during reciprocation the end turns of the coil extend beyond the end faces of the article teethand are inductively short circuited through the provision of short circuiting rings at opposite sides of the article whereby to provide i'or uniform flux distribution and insure the direction of high frequency ux to and around the roots of the teeth.

In the accompanying drawings which illustrate a preferred embodiment of the invention,

Figure 1 is a front elevation of the heat treating apparatus;

Figure 2 is a vertical section taken through the apparatus of Figure 1 to show the construction of various operating parts thereof; y

Figure 3 is a vertical section through the lower portion of the apparatus showing the mechanism for operating a main reciprocable carriage and also showing the mechanism for actuating the support for the work-piece to be heat treated;

Figure 4 is an enlarged vertical section taken substantially on the line 4-4 of Figure 5 of the heating head shown in Figure 2;

Figure 5 is a horizontal section taken substantially on the line 5 5 of Figure 2 showing the teeth of the gear to be heat treated and the complementary teeth of the heating coil;

Figure 6 is a vertical section taken through the heating coil, the coil being removed from its supporting apparatus;

Figure 'I is a transverse section taken approximately on the line 1-1 of Figure 4;

Figure 8 is an enlarged transverse section taken substantially on the line 3 3 of Figure 2 showing the mechanism for clamping the work-piece during the heating and quenching operations;

Figure 9 is an enlarged vertical section showing the mechanism for reciprocating and oscillating the heating head, and;

Figure 10 is a section taken substantially on the line III-I of Figure- 9 showing the means f for providing adjustment of the guide means for the heating head.

Referring to the accompanying drawings in which like numerals refer to like parts throughout the several views, the heat treating appal which is provided with a cylindrical piston por? tion 3 intermediate the ends thereof. The guide rods 2 are each provided with a bore 4 at one end having a cross passage 5 and a bore 8 at the opposite ends having a cross passage 1, the cross passages opening through the guide rods 2 closely adjacent the opposite sides of the piston portions 3 thereof.

The guide rods 2 reciprocally support a reciprocable carriage 3 having cylinder portions 9 which cooperate with the piston portions 3 and are sealed at their ends through suitable packing members I0 with the guide rods 2. Fluid under pressure admitted through the bores 4 and 6 causes the carriage to move upwardly or downwardly, depending of course upon which bore is supplied with uid under pressure. The cylinder portions 9 are interconnected by a cross member II having portions I2 which surround and are keyed to the lcylinder portions 9 by suitable keys I3, as shown in Figure 3. The cross member Il is cored out to provide a chamber I4 and a central cylinder housing I5. Secured within the cylinder housing I5 by means of a clamping ring I6 and cap screws I'I is a fixed cylinder I8 within which a piston rod I9 is arranged to reciprocate, the piston rod having a piston 23 fixed thereon which cooperates with the cylinder I3, the opposite ends of the cylinder being sealed through suitable packing elements 2| with the piston rod I9. The piston rod I9 is raised by admitting fluid under pressure through conduit 22 to the lower side of the piston 20 and is lowered by admitting iluid under pressure through conduit 23 to the upper side of the piston 20. In order to cushion the piston rod I9 as it nears the ends of its upward and downward strokes, the tubular packing elements 2i are enlarged at their inner ends as indicated at 24, to slidably receive cylindrical portions 25 of the piston 20. Adjacent the portions 24 are conduits 26 which .are of restricted size and function when the cylin' drical portions 25 engage with the portions 24 to slow down the piston rod and thereby provide a fluid cushion.

The upper end of the piston rod I9 is provided with a flange 21 to which a tubular housing 28 is secured by cap screws 29, this housing contains mechanism for clamping and supporting the work-piece to be heat treated.- The work-piece selected for illustration is a gear 30 having spiral external teeth and having a bore 3 I The work clamping mechanism (Figures 2 and 8) includes a recessed base 32 arranged within the housing 23 and within which a vertical rod 33 having a squared upper end, is provided for vertical movement. The lower end of the rod 33 is provided with a portion 34 which is threaded in a tubular element 35 arranged within a casing portion 36. The casing portion 36 is carried by an annular member 31 within the housing 28 and is provided with a spring 38 which engages a flange portion of the tubular member 35, the spring 33 urging the rod 33 to an uppermost position. The lower end of the tubular portion 35 projects beyond the portion 36 and is provided with an element 39 fixed thereto and having pin 40 which is engaged within a recess in the member 36 to hold the member 35 against rotation. Rotatably carried on the rod 33 between a shouldered portion 33a and a fixed nut 33h is a cylindrical member 4I having spaced shoulder portions 4Ia. Arranged about the rod 33 and pivotally supported on pins 43 are three bell crank levers 42, each bell crank lever having on one leg thereof a pivoted block 42a disposed between the two shoulder portions 4Ia. The other leg of each bell crank lever 42 has a pivoted connection through pin 44 with a radially slidable clamping member 45 guided by guideways formed in the base 32. Each of the clamping elements 45 is provided with an upstanding portion 46 surrounding the rod 33. By forcing the rod 33 downwardly the shoulder portions 4 Ia cause the clamping members 45 to move radially inwardly whereby the bore of the gear 30 may be disposed in surrounding relation with respect to the upstanding portions 46. Upon re- .lease of the downward pressure, the spring 38 causes upward movement of the rod 33 Whereby the shoulder portions 4Ia through the bell crank levers 42 move the clamping members 45 radially outwardly into clamping engagement with the bore 3I of the gear 30. Adjustment of the clamping members 45 is provided through rotation of the rod 33 in the tubular member 35.

Positioned upon thehousing 28 (Figure 4) is an annular ring 41 and an annular element 48 which cooperate through screws 49 to clamp an annular element 50 composed ofa plurality of laminations of a metal having high magnetic permeability in position. The annular element 50 is provided with a circumferential recess which houses a pair of axially aligned short circuiting rings 5I. insulated from each other and from the annular element 50.

The heating head as shown in Figures 2, 4, 5 and 6 embodies a helical coil 52 of hollow formation and having internal teeth 53 which teeth have substantially the same contour and spiral angle as the teeth of the gear to be heat treated. This helical coil forms a subject matter of and is claimed in my co-pending application, Serial No. 572,318 led Jan. 11, 1945, now Patent No. 2,435,242 issued February 3, 1948.

The coil 52 is provided with a continuous internai cooling passage 54and is supported within a recess provided in an annular radially laminated member 55 of high magnetic permeability. This cross member 62 which is rigidly mounted on the guiderods 2. The opposite ends of the cylinder are sealed by suitable packing elements 63 having which supports a tubular member 8|.

ananas slidable bearing engagement with the member 58. Fluid under pressure lis admitted through conduits 84 to the opposite ends of the cylinder 8| to provide for rapid reciprocation of the member 58 for a purpose to be subsequently described.

Arranged within the tubular member 58 is an arbor 85 comprised o! inner and outer concentric tubular conductors 58 and 81 respectively insulated from each other by an insulating sleeve 88. The upper end of the arbor is suitably supported by the supporting structure l well above the cross member 52. As shown in Figures 2 and 4 the inner conductor extends downwardly beyond the outer conductor. The tubular member 58 carries anvouter annular ring 59 which is provided with an annular conducting ring having a plurality of circumferentially spaced spring contact lingers 1| surrounding and slidably engaged with the outer conductor 81. Arranged within the annular conducting ring 88 is an inner annular conducting ring 12 having a plurality of circumferentlally spaced spring contact fingers 18 surrounding and slidably engaged with the extending end of the inner conductor 55, the inner conducting ring 12 having an annular passage 14 therein. The inner and outer conducting rings 12 and 88 respectively are insulated from eachother by suitable insulation 15 and are held in place within the member 58 by a clamping plate 15 suitably secured to the member 58. The conducting rings 12 and 89 are electrically connected with the ends of the helical coil 52 through horizontal inner and outer concentric conducting elements 11 and 18 respectively which are insulated from each other and are connected with vertical inner and outer concentric conductor elements 19 and 80 which are insulated from each other. The upper end of the helical coil 52 is connected through a conducting element 8l which is connected with the inner conducting element 18 and is insulated from the outer conducting element 80 and the annular casing 58 as shown in Figure 2.. The lower end of the helical coil 52 is connected by a conducting element 82 through a vertical rod 88 which is clamped within the outer conducting element 80 in electrical engagement therewith. The horizontal conducting element 11, the vertical conducting element 19 and the conducting element 8| are provided with interconnecting passages 84 The passage of the element 8| connects with the passage 54 of the coil 52 and the passage of the horizontal conductor 11 connects with the annular passage 14 of the inner conducting ring 12. The lower conducting element 82 is provided with a passage 85 which connects with the lower end of the coil passage 54 and is provided with a connecting conduit 88. Extending through the member 59 and insulated therefrom is a tubular member 81 having threaded connection with the inner conducting ring 12 and a passageway 88 connecting with the passage 14 of the inner conducting ring 12. A conduit 89 is connected with the passageway 88. Suitable cooling iluid is fed through the conduit 89 from whence it travels through passages 88, 14 and 84 and thence through the coil passage 54 and discharges through the passageway 85 of the conducting element 82 and the conduit 85 to cool the coil 52. Threadably secured within the extending end of the inner conductor 55 is a sleeve 90 The tubu' lar member 9| is insulated from the sleeve 80. Secured by means of a nut 82 to the lower end of the member 9| is an annular plate 88 having an l'annular sleeve 84 thereon and a` plate 85 supported on the sleeve 84. Surrounding the sleeve 84 and clamped between the plates 88 and 85 is an annular laminated member 96 of high magnetic permeability which supports a pair oi' axially aligned hollow short circuiting rings 81, the rings 81 being insulated from each other.

Extending downwardly through the inner conductor is a conduit 88 which is threadably connected with the bore of the member 8|, the

portion of the bore of the member 8| with which the conduit 88 is connected being of reduced diameter as indicated at 88. The conduit 88 above its connection with the bore is circumferentially spaced from the bore to provide an annular passage |00 which connects with the bore |0| of the inner .conductor 68. The plate 93 is provided with a pin |02 threaded into a member |08 which carries a pin |04 threaded into the upper short circulting ring 81, the member |03 being also provided with a pin |05 threaded into the lower conductor ring 81. The pins |02, |04 and |05 are provided with passages |06, passages of the pins |04 and |05 being interconnected by a passage |01 in the member |03, and the passage in the pin |02 being interconnected with the bore 88 through a passage |08 formed'in the plate 98 and the tubular member 8|. Ay similar arrangement is provided diametricallyfoppos'ite the pin members just described to provide a passage |08 from the upper short circuiting rings 81. through the plate 98 and thence" through the wall of the tubular member 8| into connection with the circumferential space |00. The space within the lower short circuiting ring 81 is connected with the passage |09 through a passage ||0. Cooling fluid is circulated' through the bore |.0| of the inner conductor 58 and travels through the circumferential space |00, where it flows through passages |09 and ||0 to the interior of the short circuiting rings 91 to maintain the same cool and discharges therefrom through the passages |08, |01 and |08 to the bore 98 of the member 9| where it discharges through the conduit 88 (Figure 7). y.'

Assuming the gear 30,` to be in the position shown in Figure 2, thecoil 52 is reciprocated through the reciprocable tubular member 59 at a relatively high speed tojeliminate the variations in heat application which result from the ilux variations which are due to the necessity of providing insulation between the turns in the coil 52. The stroke of the tubular member 59 is relatively short. Inasmuch as the gear shown for illustration is of the spiral type, the teeth of the coil 52 are caused during reciprocation to parallel the teeth of the gear by means of a spiral guide element carried by the upper end of the reciprocable member 59 and having guide portions in slidable engagement with spiral splines I2 which 'are formed on a sleeve member ||8, the sleeve member ||3 being held in fixed position by a housing ||4 secured by screws ||5 to the cross member 52.

By loosening the nut ||6 which holds the guide sleeve ||8 in fixed position and by loosening the nut ||1 which holds the guide element in xed position and then by adjusting the screws ||8 the guide element and the guide sleeve ||8 may be rotated together a slight amount, to rotate the heating head a predetermined amount for accurate alignment of the teeth of the coil 52 so as to provide for proper spacing of the teeth of the coil with the teeth of the gear 80,. Also, guide element and guide sleeve ||8 are removable for replacement by other guide As shown in Figure 4, the lowermost of the upper short circuiting rings 9| is provided with spiral teeth II9 and the uppermost of the lower short circuiting rings is provided Withspiral teeth |20, the teeth I|9 and |20 being complemental to the teeth of the coil 52.

In the operation of the apparatus, the gear 30 is moved upwardly into initial registration with the teeth of the coil 52 and in order to provide for this registration since the teeth of the gear and the coil, it is necessary to effect a rotation of the gear during this movement. In order lto provide for this rotation and proper registration, the lower end of the piston rod I9 which projects beyond the cylinder I8 is provided with a spirally splined element I2|, the splines of which register with corresponding splines of a guide sleeve |22. The guide sleeve |22 is held in xed position by a suitable clamping plate |23 which is secured to a' portion |24 of the supporting structure l. The splined element |2I lits within the end of the piston rod |9 and is removably secured thereto by a threaded collar |25 and is held against relative rotation by a key |26. The splined element I 2| and the guide sleeve |22 as in the case of the guide element I|| and sleeve 3 are interchangeable with other guide elements and sleeves having interengaging splines of the same spiral angle as the teeth of the gear to be heat treated. Obviously, during upward movement of the piston rod |9 the guide element |2| and guide sleeve |22 cause the gear 30 to rotate the desired amount whereby to register teeth 30 thereof and the teeth |20 of the lower short circulating rings 5I with the teeth of the coil 52.

The quenching mechanism which forms the subject matter of my co-pending application Serial No. 572,315 filed Jan. 11, 1945 is carried by the cross member II of the carriage 8. This mechanism comprises a manifold |21 secured to the cross member and having spaced inner and outer annular elements |28 and |29 secured thereto. Clamped between the upper ends of these elements is an annular quench distributing ring |30 having spiral teeth corresponding to the teeth of the gear to be heat treated.v The quench ring |30 is removably secured to these elements by a clamping ring |3| to provide for interchange with other quenching rings in which the teeth thereof correspond to the teeth of the particular gear to be heat treated. Quenching fluid under pressure is introduced into the manifold |21 through vconduits |32 and the quenching uid iiows upwardly through the space between the annular elements |28 and |29 and is discharged through elongated orifices |33 in the'ring |30 to direct quenching fluid against the heated surfaces of each tooth of the gear 30.

As shown in Figure 3 the teeth of the gear 30 when the piston rod I9 is in its lowermost position, are registered with the teeth of the quenching ring |30. In the operation of the apparatus described, the carriage 8 initially is in its lowermost position, that is the carriage is downwardly. positioned with respect to the uppermost position shown in Figure 1 and, in this position, the piston rod I9 is in its lowermost 8 position whereby to provide a space between the gear clamping mechanism and the heating head for removal and positioning of a gear for heat treatment. Assuming the elements to be in these positions, the gear is first disposed about the rod 33 and the rod 33 is moved downwardly to permit/the upstanding portions 48 of the clamping mechanism to be disposed within the bore 3| oi the gear 30. Upon release of the downward pressure on the rod 33, the spring .38 moves the rod 33 upwardly thus causing the clamping jaws 45 to move radially outwardly to securely engage the bore 3| of the gear and thereby hold the gear in predetermined fixed position and axially centered with respect to the heating head and the quenching ring |30. Suitable gear locating pins |34 may be utilized to cooperate with and additionally locate the gear in its proper position.

The carriage is then moved upwardly through suitable control mechanism (not shown) which controls the ow of actuating fluid to the cylinders 9 of the carriage to effect this movement. The uppermost position of the carriage is shown in Figure 2, suitable stops being provided on the guide rods 2 to predetermine this position. Fluid under pressure is then admitted by the control mechanism into the cylinder I8 to cause the piston rod I9 to move upwardly to its uppermost position, during which movement as previously described, the gear is rotated to register the teeth thereof and the teeth of the lowermost short circuiting ring 5| with the teeth 53 of the coil 52.

Fluid under pressure is then admitted to the cylinder 6| through first one and then the other of the conduits 6l by means of suitable control mechanism (not shown) to cause the tubular member 59 to reciprocate at a relatively high speed. During this reciprocation the guide element I and the guide sleeve I I2 cause the teeth of the coil 52 to oscillate and have reciprocal movement parallel to the teeth of the gear. At the time the coil 52 is started to reciprocate as just described, the coil 52 is energized from a source of high frequency current such as from a suitable transformer of the type shown in my co-pending application Serial No. 538,975 filed June 6, 1944 now Patent No. 2,420,449 issued May 13, 1947. The coil 52 is thus provided with a small amount of circumferential oscillatory movement which is but a small part of a revolution and is dependent un the helix angle for the length of stroke whereby to eliminate variations in the heating of the surfaces of the gear teeth due to the iiux variations arising out of the necessity of providing insulation between the turns of the coil.

It will be noted that the coil 52 is of greater length than the width of the gear face and that the end turns of the coil are projected over the short circuiting rings 5| and 9| in such manner that at each end of the short stroke of the coil 52, the end turns will be in surrounding relation with respect to at least one of the short circuiting rings 5| at the lower limit. This short circuiting arrangement provides an effective means through inductive short circuiting of the end turns of the coil for eliminating the variations of flux due to the end turn configuration of the coil, thus enabling the application to the gear face and teeth thereof of a uniform flux throughout the diameter of the gear.

After the faces of the gear teeth have been accurately heated to hardening temperature the control mechanism, after such suitable time delay as is deemed necessary, causes the piston rod I9 to move downwardly to its lowermost position thus bringing the teeth of the gear into registration with the teeth of the quenching ring |30 at which time the quenching fluid is admitted through the conduits |32. The quenching iiuid after quenching the heated faces flows downwardly within the inner element |28 and thence through openings |36 into the chamber i4 of the cross member where it discharges through' a suitable conduit |31.

It is to be borne in mind that the arbor 66 is stationary and the tubular member 59 and spring conducting iingers and 13 reciprocate relative to the arbor. A suitable collar |40 fixed within member 59 provides means for maintaining the arbor 65 and member 59 in axial alignment.

After the quenching operation the gear is then removed and replaced with another gear to be heat treated through repetition of the cycle just described.

While I have described the treatment of a helical type gear it will be obvious that the apparatus described can be satisfactorily used for the heat treatment of spur gears, splines and other circumferentially toothed members. The term gear as used in the claims is to be construed to mean any circumferentially toothed article.

While the teeth of the coil 52 are shown to have the same contour as the teeth of the gear selected for illustration, the coil teeth may be varied somewhat to obtain a desired predetermined heating effect. Also, the coil teeth may be varied to provide for hardening the tooth sections only,

leaving the root sections unhardened and in other cases to provide for massive heat treatment for wear resistance and high strength. It is to be understood also that the principles herein disclosed are applicable to the treatment of internally toothed or splined structures.

While I have not shown the control mechanism and circuits for the various parts, it is to be understood that the same may be of any desired type to bring about the operations described.

AIt will be obvious that various changes may be made in the detailed construction and arrangement of the parts described without departing from the spirit and substance of the invention, the scope of which is defined by the appended claims.

What is claimed is:

1. In an apparatus for heating circumferentially toothed Workpieces by electromagnetic induction heating, a support for rigidly holding the toothed workpiece to be heated, an energizable helical inducing coil having circumferential teeth corresponding in`number and spacing to the teeth of the workpiece, the teeth of one of the coil and workpiece being external and the teeth of the other being internal, means for eifecting relative axial movement between said support and the workpiece to register the teeth of said workpiece and the coil with each tooth of the workpiece disposed between and spaced from a pair of adjacent teeth of said coil, and means for effecting rapid relative reciprocatory movement between the teeth of the workpiece and coil while in registration and during energization of said coil.

2. In an :apparatus for heating circumferentially toothed workpieces by electromagnetic induction heating, a support for rigidly holding the toothed workpiece to be heated, an energiz- 10 able helical inducing coil having circumferential teeth corresponding in number and spacing to the teeth of the workpiece, the teeth of one of the coil and workpiece being external and the teeth of the other being internal, means for effecting relative axial movement between said support and the workpiece to register the teeth of said workpiece and the coil with each tooth of the workpiece disposed between and spaced from duction heating, a support for rigidly holding theA toothed workpiece to bev heated, an energizable helical inducing coil having circumferential teeth corresponding in number and spacing to the teeth of the workpiece, the teeth of one of the coil and workpiece being external and the teeth of the other being internal, means for eifecting relative axial movement `between said support and the workpiece to register the teeth of said workpiece and the coil with ea-ch tooth of the workpiece disposed between and spaced from a pair of adjacent teeth of said coil, and means for effecting rapid relative reciprocatory movement between the teeth of the work-piece and coil while in registration and during energization of said coil, the axial width of said coil being greater than the axial width of the tooth faces of the workpiece and the stroke of said reciprocatory movement being such as to maintain the workpiece within the axial limits of said coil during said reciprocatory movement.

4.,In an apparatus for heating circumferential-1y toothed workpieces by electromagnetic induction heating, a support for rigidly holding the toothed workpiece to .be heated, an energizable helical inducing coil having circumferential -teeth corresponding in number and spacing but of lesser 'thickness than the teeth of the workpiece, the length of the teeth of said coil lbeing greater than the length of the teeth of the workpiece, the teeth of one of the coil and workpiece being external and the teeth of the other being internal, a'support for rigidly holding said coil, said supports maintaining the workpiece and said coil in axial alignment, means for axially moving one of said supports toward the other support to register the teeth of the workpiece and said coil with each tooth of one spaced from adjacent teeth of the other, means for rapidly reciprocating said other support, the reciprocable stroke thereof being of such length that the workpiece teeth are maintained within the coni'lnes of the length of the teeth of said coil, and means for constraining the teeth of the workpiece and said coil to parallel relationship during the reciprocating movement.

5. In Aan apparatus for heating circumferentially toothed workpieces by electromagnetic induction heating, a support for rigidly holding the toothed workpiece to be heated, an energizable helical inducing coil having circumferential teeth corresponding in number and spacing but of lesser thickness than the teeth of the workpiece, the length of the teeth of said coil being greater than the length of the teeth of the workpiece, the teeth of one of the coil and workpiece being external and the teeth of the other being internal, a support for rigidly holding said coil, said supports maintaining the workpiece and said coil in axial alignment, means for axially moving one of said supports toward the other support to register the teeth of the workpiece and said coil with each tooth of one spaced from adjacent teeth of the other, means for rapidly reciprocating said other support, the reciprocable stroke thereof being of such length that the workpiece teeth are maintained within the connes of the length of the teeth of said coil, a supporting structure -for said other support, and cooperable guide elements on said supporting structure having intertting circumferential portions, said interiitting portions being parallel to the teeth of the workpiece and said coil for maintaining the spacing between said teeth during the reciprocating movement.

6. In an apparatus for heating the teethof spiral gears `by electromagnetic induction heating, a helical induction heating coil having spiral teeth corresponding in number, spacing and spiral angle to the teeth of the gear, the teeth of one of the coil and gear :being external and the teeth of the other being internal, the teeth of said coil being of greater length than the teeth of the gear, and the teeth of the gear and coil being registerable with each other with each tooth of one spaced from adjacent teeth of the other, a support for said coil, a support for the gear, and means for effecting rapid combined oscillatory and reclprocable movement of one of said supports for oscillating and reciprocating one of said gear and coil relative to the other while said teeth are in registration.

'7. In an apparatus for heating the teeth of spiral gears by electromagnetic induction heating, a helical induction heating coil having spiral teeth corresponding in number, spacing and spiral angle to the teeth of the gear, the teeth of one of the gear and coil being external and the teeth of the other being internal, the teeth of the coil being of `greater length than the teeth of the gear, a support for the gear coaxial therewitlif a support for said coil coaxial therewith, said supports being axially aligned with each other, separate guide means for guiding each of said supports for axial movement, cooperable interengaged splined elements carried by each support and its associated guide means and having spiral splines of the same spiral angle as said teeth for rotatlvely guiding said supports during axial movement thereof, actuating means for moving one of -said supports axially toward the other to effect registration of the teeth of the gear and said coil with the teeth of each spaced from the teeth of the other, and means for rapidly reciprocating the other of said supports whereby to relatively reci-procate and oscillate the teeth of the gear and said coil, the .reciprocable stroke thereof being such that the teeth of the gear are maintained within the confines of the teeth of said coil during said reciprocation.

8. In an apparatus for heating metallic articles by electromagnetic induction heating, an energizable helical inducing coil of greater axial width than the surface of the article to be heated, means for supporting the article adjacent and Within the axial limits of said coil, and short circuiting rings at opposite sides of the article so supported and adjacent said coil in spaced relation therewith, said rings extending beyond the axial limits of said coil for inductivelyshort circuiting the end turns of said coil during enereach other and said ring, one of said conductors extending axially beyond the other, the support for said coil having contactors insulated from each other, respectively, electrically connected with the ends of said coil and sldably engaged with the ends of said conductors, and means for reciprocating one of said supports relative to the other to effect relative reciprocation between said coil and ring.

10. In an apparatus for heating the surfaces of the teeth of spiral gears, a helical inducing coil having teeth corresponding in number, spacing and spiral angle with, but of lesser thickness than the teeth of the gear to be heated, a support for said coil, a support for holdingthe gear in axial alignment with said coil and in normally axially spaced relation therewith, supporting structures for said supports, means for ,axially moving one of the supports toward and away from the other, and cooperable elements carried by said one support and its supporting structure and having interengaged splines of the same spiral angle as said teeth for rotatively guiding the teeth of the gear and coil into and out of spaced registration during the respective movements of said one support toward and away from the other support.

l1. In an apparatus for heating the surfaces of the teeth of spiral gears, a helical inducing coil having teeth corresponding in number, spacing and spiral angle with, but of lesser thickness than the teeth of the gear to be heated, a support for said coil, a support for holding the gear in axial alignment with said coil and in normally axially spaced relation therewith, supporting structures for said supports, means for axially moving one of the supports toward and away from the other, cooperable elements carried by said one support and its supporting structure and having interengaged splines of the same spiral angle as said teeth for rotatively guiding the teeth of the gear and coil into and out; of spaced registration during the respective movements of said one support toward and away from the other support, and means rotatively adjusting said cooperable elements relative to said one support and its supporting structure.

12. In an apparatus for surface heating a toothed gear workpiece by electromagnetic induction heating, an energizable helical induction heating coil having its turns axially spaced apart and having teeth matching the teeth of said workpiece, one of said coil and workpiece having an external surface and the other having an internal surface and the axial width of said coil being materially greater than the axial width of the workpiece surface to be heated, means for relatively moving said coil and the workpiece to position said external and internal surfaces and teeth in adjacent operative heating relation with the toothed surface of the workpiece within the icoil and while the teeth of the workpiece and coil 13 are intermeshed for effecting rapid relative reciprocatory movements between said coil and the workpiece while keeping the circumferential relationship of the teeth ofthe workpiece and coil constant, the reciprocatory stroke being such that the workpiece with its teeth is maintained within said axial limits of the teeth of said coil during said reciprocatory movements.

13. In an apparatus for surface heating a toothed gear workpiece by electromagnetic induction heating, an energizable helical induction heating coil having its turns axially spaced apart and having teeth matching the teeth of said workpiece, one of said coil and workpiece having an external surface and the other having an internal surface, means for relatively moving said coil and the workpiece to position said external and internal surfaces and teeth in adjacent operative heating relation, the one within the other, said coil being of such axial width that in said operative heating relation the end turns thereof are disposed axially beyond the axial limits of the workpiece surface to be heated, and means for effecting repeated rapid reciprocatory movements v 14 supports until the workpiece is within the axial limits of the length of said coil, and other power means for reciprocating one of said workpiece and coil supports rapidly while maintaining the workpiece within the limits of length of said coil.

16. In an apparatus for heating the circumferential surface of a workpiece by electromagnetic induction heating, a support for holding the workpiece to be heated, an energizable inducing coil having a length greater than the length of said workpiece, a support for said coil coaxial with said workpiece support, power means for axially moving one of said workpiece and coil supports until the workpiece is within the axial limits of the length of said coil, and other power means for reciprocating one of said workpiece and coil supports rapidly while maintaining the workpiece within the limits of length of said coil, said workpiece and coil having mating teeth, and interacting means associated with said supports and power means for bringing the teeth of the workpiece and coil into spaced meshing relationship for heating and so maintaining them during the reciprocatory movement.

between said coil and workpiece while maintain- "17- In an apparatus for heating the circuming the teeth of the workpiece and coil intermeshed and at constant spacing within the axial limits of said coil during energization of said coil.

14. In an apparatus for surface heating a toothed gear workpiece by electromagnetic in 3o length of said workpiece, a support for said coill duction heating, an energizable helical induction heatingcoil having its turns axially spaced apart and having teeth matching the teeth of said workpiece, one of said coil and workpiece having ferential surface of a workpiece by velectromagnetic induction heating, a support for holding the workpiece to be heated, an energizable inducing coil having a length greater than the coaxial with said workpiece support, power means for axially moving one of said workpiece and coil supports until the workpiece is within the axial limits of the length oi' said coil, and other power an external surface and the other having an inmeans for reciprocating one 0f Said workpiece ternal surface, means for relatively moving said coil and the workpiece to position said external and internal surfaces and teeth in adjacent operative heating relation, the one within the other,

and coil supports rapidly while maintaining the workpiece within the limits of length of said coil, said workpiece and coil having mating helical teeth, and interacting means between said sup said con being of such axial width that in said 40 pms and POW means for bringing the Spiral operative heating relation the end turns thereof are disposed axially beyond the axial limits of the workpiece surface to be heated, inductive short circuiting rings at opposite sides of the surface of the workpiece to be heated and in spaced overlapping relation with said end turns of said coil, and means for effecting repeated rapid relative reciprocatory movements between said coil and the workpiece of such minimum stroke that said end turns and short circuiting rings are maintained in overlapping relation during said movements.

15. In an apparatus for heating the circumferential surface of a workpiece by electromagnetic induction heating, a support for holding the workpiece to be heated. an energizable inducing coil having a length greater than the length of said workpiece. a support for said coil coaxial with said workpiece support, power means for axially moving one oi' said workpiece and coil 5 teeth of the workpiece and coil into spaced meshing relationship for heating and so maintaining them during the reciprocatory movement.

HOWARD E. SOMES.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Great Braam sept. 2o, 1937 

